#!/usr/bin/python

# This is statement is required by the build system to query build info
if __name__ == '__build__':
    raise Exception

'''
fog.c from the Redbook examples.
Converted to Python by Jason L. Petrone 7/00

/*
 * Copyright (c) 1993-1997, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED
 * Permission to use, copy, modify, and distribute this software for
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission.
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * US Government Users Restricted Rights
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
 */
'''

'''
/*
 *  fog.c
 *  This program draws 5 red spheres, each at a different
 *  z distance from the eye, in different types of fog.
 *  Pressing the f key chooses between 3 types of
 *  fog:  exponential, exponential squared, and linear.
 *  In this program, there is a fixed density value, as well
 *  as fixed start and end values for the linear fog.
 */
'''

import sys

try:
    from OpenGL.GLUT import *
    from OpenGL.GL import *
except ImportError:
    print('''
ERROR: PyOpenGL not installed properly.
        ''')
    sys.exit()


# Initialize depth buffer, fog, light source,
#  material property, and lighting model.

def init():
    position = [0.5, 0.5, 3.0, 0.0]
    glEnable(GL_DEPTH_TEST)
    glLightfv(GL_LIGHT0, GL_POSITION, position)
    glEnable(GL_LIGHTING)
    glEnable(GL_LIGHT0)
    mat = [0.1745, 0.01175, 0.01175, 1.0]
    glMaterialfv(GL_FRONT, GL_AMBIENT, mat)
    mat[0] = 0.61424
    mat[1] = 0.04136
    mat[2] = 0.04136
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat)
    mat[0] = 0.727811
    mat[1] = 0.626959
    mat[2] = 0.626959
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat)
    glMaterialf(GL_FRONT, GL_SHININESS, 0.6 * 128.0)

    glEnable(GL_FOG)
    fogColor = [0.5, 0.5, 0.5, 1.0]

    global fogMode
    fogMode = GL_EXP
    glFogi(GL_FOG_MODE, fogMode)
    glFogfv(GL_FOG_COLOR, fogColor)
    glFogf(GL_FOG_DENSITY, 0.35)
    glHint(GL_FOG_HINT, GL_DONT_CARE)
    glFogf(GL_FOG_START, 1.0)
    glFogf(GL_FOG_END, 5.0)
    glClearColor(0.5, 0.5, 0.5, 1.0)


def renderSphere(x, y, z):
    glPushMatrix()
    glTranslatef(x, y, z)
    glutSolidSphere(0.4, 16, 16)
    glPopMatrix()


# display() draws 5 spheres at different z positions.
def display():
    print('redisplay')
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    renderSphere(-2., -0.5, -1.0)
    renderSphere(-1., -0.5, -2.0)
    renderSphere(0., -0.5, -3.0)
    renderSphere(1., -0.5, -4.0)
    renderSphere(2., -0.5, -5.0)
    glFlush()


def reshape(w, h):
    glViewport(0, 0, w, h)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    if w <= h:
        glOrtho(-2.5, 2.5, -2.5 * h / w, 2.5 * h / w, -10.0, 10.0)
    else:
        glOrtho(-2.5 * w / h, 2.5 * w / h, -2.5, 2.5, -10.0, 10.0)
    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()


def keyboard(key, x, y):
    global fogMode
    if key in [b'f', b'F']:
        if fogMode == GL_EXP:
            fogMode = GL_EXP2;
            print("Fog mode is GL_EXP2")
        elif fogMode == GL_EXP2:
            fogMode = GL_LINEAR
            print("Fog mode is GL_LINEAR")
        elif fogMode == GL_LINEAR:
            fogMode = GL_EXP
            print("Fog mode is GL_EXP")
        glFogi(GL_FOG_MODE, fogMode)
        glutPostRedisplay()

    elif ord(key) == 27:
        sys.exit()


#  Main Loop
#  Open window with initial window size, title bar,
#  RGBA display mode, depth buffer, and handle input events.

glutInit(sys.argv)
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(500, 500)
glutCreateWindow('fog')
init()
glutReshapeFunc(reshape)
glutKeyboardFunc(keyboard)
glutDisplayFunc(display)
glutMainLoop()
